Made zone return errors and http idempotent

The Zone DB tells you if you have a duplicate or missing record, but
the HTTP server smoothes these over.

server/http.go

@@ -48,7 +48,13 @@ func ListenHttp(domain string, db Zone, port int) {
 				Info.Printf("Adding %s (%s) -> %s", name, local_ip, weave_cidr)
 				err = db.AddRecord(identifier, name, ip, weave_ip, subnet)
 				if err != nil {
-					http.Error(w, err.Error(), http.StatusConflict)
+					dup, ok := err.(DuplicateError)
+					if !ok {
+						Error.Print("Unexpected error from DB", err)
+						http.Error(w, "Internal error", http.StatusInternalServerError)
+					} else if dup.Ident != identifier {
+						http.Error(w, err.Error(), http.StatusConflict)
+					}
 					return
 				}
 			} else {
@@ -70,8 +76,11 @@ func ListenHttp(domain string, db Zone, port int) {
 			Info.Printf("Deleting %s (%s)", identifier, weave_ipstr)
 			err = db.DeleteRecord(identifier, weave_ip)
 			if err != nil {
-				http.Error(w, err.Error(), http.StatusBadRequest)
-				return
+				if _, ok := err.(LookupError); !ok {
+					Error.Print("Unexpected error from DB", err)
+					http.Error(w, "Internal error", http.StatusInternalServerError)
+					return
+				}
 			}
 		default:
 			Warning.Println("Unexpected http method", r.Method)

server/http_test.go

@@ -41,7 +41,7 @@ func TestHttp(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if resp.StatusCode != 200 {
+	if resp.StatusCode != http.StatusOK {
 		t.Fatal("Unexpected http response", resp.Status)
 	}
 
@@ -55,12 +55,23 @@ func TestHttp(t *testing.T) {
 		t.Fatal("Unexpected result for", success_test_name, ip)
 	}
 
-	// Now try adding the same address again - should fail
+	// Adding exactly the same address should be OK
 	resp, err = genForm("PUT", addr_url,
 		url.Values{"fqdn": {success_test_name}, "local_ip": {docker_ip}, "routing_prefix": {addr_parts[1]}})
 	if err != nil {
 		t.Fatal(err)
 	}
+	if resp.StatusCode != http.StatusOK {
+		t.Fatal("Expected duplicate add to succeed with 200 OK")
+	}
+
+	// Now try adding the same address again with a different ident - should fail
+	other_url := fmt.Sprintf("http://localhost:%d/name/%s/%s", port, "other", addr_parts[0])
+	resp, err = genForm("PUT", other_url,
+		url.Values{"fqdn": {success_test_name}, "local_ip": {docker_ip}, "routing_prefix": {addr_parts[1]}})
+	if err != nil {
+		t.Fatal(err)
+	}
 	if resp.StatusCode != http.StatusConflict {
 		t.Fatal("Unexpected http response", resp.Status)
 	}
@@ -80,6 +91,15 @@ func TestHttp(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	// Delete the address again, it should accept this
+	resp, err = genForm("DELETE", addr_url, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		t.Fatal("Unexpected http response", resp.Status)
+	}
+
 	// Would like to shut down the http server at the end of this test
 	// but it's complicated.
 	// See https://groups.google.com/forum/#!topic/golang-nuts/vLHWa5sHnCE